cpupower-info.1: describe the --perf-bias option

The cpupower-info(1) man page only mentions the short form of the
'--perf-bias' option in the synopsys, but the long form is not documented
and its effect is not explained.

cpupower-info.c:
     {"perf-bias", optional_argument, NULL, 'b'},

Signed-off-by: Roberto Ricci <io@r-ricci.it>
Link: https://lore.kernel.org/r/20260324223921.14317-5-io@r-ricci.it
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

Author: r-ricci

tools/power/cpupower/man/cpupower-info.1

@@ -3,7 +3,7 @@
 cpupower\-info \- Shows processor power related kernel or hardware configurations
 .SH SYNOPSIS
 .ft B
-.B cpupower info [ \-b ]
+.B cpupower info [\fIoptions\fP]
 
 .SH DESCRIPTION
 \fBcpupower info \fP shows kernel configurations or processor hardware
@@ -13,6 +13,13 @@ Some options are platform wide, some affect single cores. By default values
 of core zero are displayed only. cpupower --cpu all cpuinfo will show the
 settings of all cores, see cpupower(1) how to choose specific cores.
 
+.SH "OPTIONS"
+.LP
+.TP
+\fB\-b\fR \fB\-\-perf-bias\fR
+Gets the current performance bias value.
+.TP
+
 .SH "SEE ALSO"
 Options are described in detail in: